Polyaniline (PANI)-a-Fe2O3 nanocomposites (NCs) have been synthesized by chemical oxidative in situ polymerization of aniline in presence of a-Fe2O3 nanoparticles at 5 degrees C using (NH4)2S2O8 as an oxidant in an aqueous solution of sodium dodecylbenzene sulphonic acid (SDBS), as surfactant and dopant under N2 atmosphere. The room temperature conductivity of NCs decreases and coercive force (Hc) increases with an increase addition of a-Fe2O3 in PANI matrix. The result of FTIR and TGA shows that the interaction between a-Fe2O3 particles and PANI matrix could improve the thermal stability of NCs. NCs demonstrate the superparamagnetic behavior. The performance of PANI and PANI-a-Fe2O3 NCs as protective coating, against corrosion of 316LN stainless steel in 3.5% NaCl was assessed by potentiodynamic polarization technique. The study shows a good corrosion inhibition effect of both the coatings. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013